含側鏈液晶的聚電解質與其在陰離子交換膜之應用

本論文使用聚(4-乙烯吡啶)以及嵌段共聚苯乙烯及聚(4-乙烯吡啶)高分子電解質為陰離子交換膜的主要結構，並同時掛有側鏈液晶分子。聚(4-乙烯吡啶)上的陽離子是和帶有末端溴官能基的液晶分子反應而得。本實驗對此陰離子交換膜的性質做了系統性的研究，例如：吸水程度、膨潤量、離子交換容積、離子傳導度以及在鹼性環境下的穩定度。當使用聚(4-乙烯吡啶)作為陰離子交換膜的高分子結構時，僅有較低的側鏈液晶含量可以在水中維持膜的完整度，相較之下，使用嵌段共聚苯乙烯及聚(4-乙烯吡啶)時在較高的側鏈液晶含量在水中仍然可以有很好的完整度，這說明了嵌段共聚高分子在嚴苛環境下擁有的優勢。帶有41%側鏈液晶接枝比例的嵌段共聚苯乙烯及聚(4-乙烯吡啶)擁有3×〖10〗^(-4) S〖cm〗^(-1)離子傳導度，儘管吸水程度以及膨潤量分別只有不到9%以及3%，與其有相同接枝比例的帶有側鏈甲基陰離子交換膜則分別有28%以及9%。這說明了側鏈液晶分子的引入增加了陰離子交換膜結構的穩定性，也同時提供了有效的離子傳導通道儘管只有極低的吸水程度，在熱穩定性以及強鹼環境下的穩定性也有更好的表現。

關鍵字

嵌段共聚苯乙烯及聚(4-乙烯吡啶) ；側鏈液晶；陰離子交換膜

並列摘要

In this work, anion exchange membranes (AEMs) based on polyelectrolytes bearing pendant mesogenic groups are prepared using poly(4-vinylpyridine)(P4VP) and poly(styrene)-block-poly(4-vinylpyridine)(PS-b-P4VP) as the polymer backbones. The pyridinium cations were produced upon the introduction of bromide-terminated mesogen groups to the P4VP monomer unit. The membrane quality and integrity, as well as the hydroxide transport properties, including swelling ratio, water uptake, ion exchange capacity (IEC), ionic conductivity and alkaline stability were evaluated. When using P4VP homopolymer as the backbone, only the AEM with low mesogen content would sustain the integrity in water. By contrast, PS-b-P4VP could offer the corresponding AEMs good integrity in water even with high degree of functionalization. PS-b-P4VP with 45% degree of functionalization of mesogenic groups exhibited an ionic conductivity of 3 x 10-4 S cm-1 with only 9 wt% water uptake and less than 3% swelling ratio. On the other hand, the reference AEM with similar degree of functionalization of methyl groups exhibited 28 wt% water uptake and 9% swelling ratio. The use of mesogenic group should enhance the dimensional stability and facilitate effective hydroxide transport pathways even with low water uptake. The side mesogenic groups also found to enhance the thermal stability and the alkaline stability of the AEM.

並列關鍵字

Poly(styrene)-block-poly(4-vinylpyridine) ； pendant mesogen ； anion exchange membrane

參考文獻

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國際替代計量

含側鏈液晶的聚電解質與其在陰離子交換膜之應用

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